It is known that tertiary phosphines are synthesizable by various techniques, including the reduction of tertiary phosphine oxides. The tertiary phosphine oxide reduction processes that have been used in the past have included the processes of U.S. Pat. Nos. 3,261,871 (Fritzche et al. I), 3,280,195 (Fritzche et al. II), 3,847,999 (Gardner et al.), 4,008,282 (Townsend et al.), 4,113,783 (Malpass et al.), and 4,131,624 (Davis et al.); Issleib et al., CA 53:9879c; Fritzche et al. III, CA 61:8335f; Koester et al., CA 63:8398h; and G. M. Kosolapoff et al., Organic Phosphorus Compounds, Vol. 1, Wiley Interscience Publishers (New York), 1972, pp. 45-47, as well as processes wherein the oxide has been converted to the tertiary phosphine via an intermediate. One of these processes, a process of Issleib et al., involves reducing triphenylphosphine oxide with aluminum hydride in ether.
Some of these processes have achieved some measure of success as commercially feasible techniques, but there is still a need for an economical, efficient method of reducing tertiary phosphine oxides to the corresponding phosphines.